What is a photon?

#1
I guess we've all seen those cardboard cut outs representing an electromagnetic wave, with the electric & magnetic fields at right angles to each other. We're told that a photon is a 'Packet' of electromagnetic energy, the thing I would like to know is...How many of these squiggles of waves go to make up a photon?

Is it one wavelength? Does it depend on the wavelength? How does a photon of Gamma radiation differ from an infra red one?

Presumably, a photon of Gamma radiation would be 'Shorter' than an infra red one?

These electric & magnetic fields, are they thin & sharp as represented on the cardboard models? Or are they more of a general 'Splurge'.

Any non technical simple to understand answers would be greatly appreciated.
 
#2
A photon can be described as a quanta of electromagnetic energy. The frequency is proportional to the amount of energy a photon has. Long wavelength=lower energy than short wavelength.
 

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#3
Its based on energy (usually measured in eV). The higher the frequency of the "light" the higher the energy content of the photos that make it up (as determined by an equation that looks like E=fxPlank Constant). Of course its been over a decade since I worked it out so I may well have mis-remembered something ;).

Shorter wavelength = higher frequency. This is why X-rays and Gamma rays are described as being ionising radiation. They contain enough energy to excite an electron so much it becomes "free" of the atom it was orbiting leaving behind a positively charged ion.
 
#5
.How many of these squiggles of waves go to make up a photon?
Light is both a wave and a particle. Because we can never know for certain the position or momentum of a particle, because [oversimplification] they're ridiculously small, they get represented by a wave peaking at the likeliest position of the particle.

Fundamentally you have disconnect yourself from the rational, orderly world of classical physics where everything makes intuitive sense. Quantum mechanics makes no concessions to what WE, as human beings, think is hard reality. There's no real point in saying everything is a wave or everything is a particle because that's absurd to our small brains. The best we can say is that it behaves as both.
 
#6
A photon is a vibrating ring (or string) of energy which can exhibit the characteristics of either a particle or a wave depending upon its mood. The most interesting thing about a photon is it's ability to transport energy from it's source to an object which absorbs the said wavelength and becomes exited by it, i.e. it gets warmed, pies mostly, or pasties, I like pies myself!
 
#7
Light is both a wave and a particle. Because we can never know for certain the position or momentum of a particle, because [oversimplification] they're ridiculously small, they get represented by a wave peaking at the likeliest position of the particle.

Fundamentally you have disconnect yourself from the rational, orderly world of classical physics where everything makes intuitive sense. Quantum mechanics makes no concessions to what WE, as human beings, think is hard reality. There's no real point in saying everything is a wave or everything is a particle because that's absurd to our small brains. The best we can say is that it behaves as both.
I don't think that is quite correct, I think we can measure either the velocity (assuming that is what you meant by momentum) or it's position, not both.
 
#8
"Direct measurement of the quantum wavefunction", Lundeen et al, Nature. June 11.

Theoretically, the wavefunction extends to infinity although this experiment seems to pick them up at about 20mm for visible light.

Presumably, a photon of Gamma radiation would be 'Shorter' than an infra red one?
"Sharper" rather than "shorter".

These electric & magnetic fields, are they thin & sharp as represented on the cardboard models? Or are they more of a general 'Splurge'.
Definitely 'splurge'.

I don't think that is quite correct, I think we can measure either the velocity (assuming that is what you meant by momentum) or it's position, not both.
It is momentum and position - and you are not quite correct either - there is a limit to the accuracy with which we can measure the combination. That does mean that there is a limit to which we can measure either as well. Theoretically, it is down at the Plank length and up at the Plank energy but there is still a fundamental limit.
 
#9
I'm still confused here, how do you divide up photons? A radio wave may be many meters long, a Gamma ray very much shorter.

Is a photon one squiggle, many squiggles or what?

Imagine a single photon travelling through space, what is its length? It sure as shit must have one!

I suppose a single wavelength should be able to travel through space, would that be the definition of a photon?
 
#10
I guess we've all seen those cardboard cut outs representing an electromagnetic wave, with the electric & magnetic fields at right angles to each other. We're told that a photon is a 'Packet' of electromagnetic energy, the thing I would like to know is...How many of these squiggles of waves go to make up a photon?

Is it one wavelength? Does it depend on the wavelength? How does a photon of Gamma radiation differ from an infra red one?

Presumably, a photon of Gamma radiation would be 'Shorter' than an infra red one?

These electric & magnetic fields, are they thin & sharp as represented on the cardboard models? Or are they more of a general 'Splurge'.

Any non technical simple to understand answers would be greatly appreciated.
Young man, as a very old person - almost old enough to remember glass plates, the definition of a pho ton was as follows :
1 photo @ 4 x 7 = 0.0017Gm/Iinch
1 photo @ 5 x 9 = 0,0025Gm/Inch

Thus the pho ton is a variable which depends upon which size photo you require is as follows:

a pho ton is 2240lb/sq in divided by the above measurements.

But trust me. Digital is a lot lighter
 
#11
I'm still confused here, how do you divide up photons? A radio wave may be many meters long, a Gamma ray very much shorter.

Is a photon one squiggle, many squiggles or what?
Many squiggles. Getting rapidly smaller - more rapidly (even measured by wavelength) the higher the frequency.

Imagine a single photon travelling through space, what is its length? It sure as shit must have one!
Quite long, actually - look at the twin slits experiment - even at .5mm apart, the slits are going to be very far apart in wavelength terms - roughly a 1000 wavelengths. Yet you can still get interference from a single photon. As the linked paper says, you can detect the fringes of the photon wave function out to about an inch. Just to deliberately mix my units. The maths suggests that it is infinitely long - but then maths is a wee bit less useful than some people think.
 
#12
I don't think that is quite correct, I think we can measure either the velocity (assuming that is what you meant by momentum) or it's position, not both.
It is momentum and position - and you are not quite correct either - there is a limit to the accuracy with which we can measure the combination. That does mean that there is a limit to which we can measure either as well. Theoretically, it is down at the Plank length and up at the Plank energy but there is still a fundamental limit.
How sure are you? When it comes to a photon it's velocity is about light speed but it's momentum is 0.
 
#15
How sure are you? When it comes to a photon it's velocity is about light speed but it's momentum is 0.
A photon does not have momentum = 0(*); its momentum, p, is related to its energy by the expression E = p.c (where c = sol)

Note:
(*)... unless it has zero energy ... and I'm not sure it is meaningful to talk about a photon with no energy.
 
#16
Think of space as being a lake...a stone drops in and a wave radiates outwards. There are no photons in the universe, only waves of excited energy turning off and on as if travelling...the frequencies provide colours.

I'll get my coat...
 
#17
photon's are sub atomic particles that are released in the electromagnetic spectrum, there produced by everything and normal "solid" objects emit and receive photons from there surroundings in perpetual flux change, this is what
gives us the ability to see and interact with our environment

normal photon transfer occures at low levels and causes no noticable effects there are exceptions to things which dont release photons like glass in its solid state, this is covered by the fact that photon's emited travel through the medium, there are other things which have also been observed to be photon conductors but not emmiters in there normal common state, this has allowed the production of various photon receivers emitters and focusers (lenses)

the general definition of a photon is a sub atomic particle which is transfered from one atom to another and produce light effects at different wavelenghts depending on the energy quotent of the photonic particle this will also change

so in conclusion a photon is a subatomic particle that is readily emitted from an atom ....
 
#18
Now and again I leave the NAAFI in search of wonderment...then I come here, find it, panic and now I'm going back to the NAAFI!!
 
#19
Now and again I leave the NAAFI in search of wonderment...then I come here, find it, panic and now I'm going back to the NAAFI!!
why its far more fun to google a few things a then try to put them in your own words, it opens you up to new horizons, and broadens your basic understanding of things in the here and now, of course if you get anything wrong someone will spank you with why its wrong but your free to try again and again XD
 
#20
The energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ):
where k is the wave vector (where the wave number k = |k| = 2π/λ), ω = 2πν is the angular frequency, and ħ = h/2π is the reduced Planck constant.Since p points in the direction of the photon's propagation, the magnitude of the momentum is
 

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